#  Box.py
def add(x1, x2):
    a = x1 + x2
    print("a=", a)
    return a


def sub(x1, x2):
    s = x1 - x2
    print("s=", s)
    return s


def div(x1, x2):
    if (x2 == 0):
        print("false")
    else:
        d = x1 / x2
        print("d=", d)
        return d


def mul(x1,x2):
    m = x1 * x2
    print("m=", m)
    return m

